People confined to a bed or wheelchair are susceptible to decubitus ulcers, commonly known as pressure or bedsores. Sitting or lying in bed for an excessive duration of time exerts a certain degree of pressure to an area of the person's skin. This excessive pressure occludes the person's capillaries and cuts off the supply of blood to his or her tissue thus causing the aforementioned sores. Pressure sores can cause tissue necrosis and can damage muscle, bone and supporting structure, and as such can be a severe medical problem and life threatening. Fortunately, pressure sores can be avoided by simply alleviating pressure on an individual's skin through movement or weight shifting.
People that have a normal range of motion and normal sensation will experience discomfort and adjust or shift their weight prior to the formation of pressure sores. Individuals confined to a wheelchair, paraplegics or quadriplegics for example, may be capable of shifting their weight but may not have adequate sensation to know when to perform such a weight shift. It is therefore desirable that some form of external signal be communicated to people in wheelchairs to inform them that it is time to perform a weight shift in order to prevent pressure sores from forming.
Learning how to perform weight shifts on a regular basis is part of the rehabilitative process for individuals who have been recently injured. Individuals are often given simple kitchen timers to help remind them to perform weight shifts. The individual resets the timer once time expires. Although adequate in a clinical setting, such a timer becomes impractical once the individual is released. Additionally, some individuals do not possess adequate hand function to manually reset such a timer.
Wheelchairs often have a seat made of a seating surface and a back frame. The seating surface is usually either horizontal or inclined slightly backwards from the front of the seating surface to the back of the seating surface. In order to shift the weight of the person in the wheelchair, the seat may be tilted so that the weight of the user on his or her pressure points, typically the buttocks, legs, and/or back, is relieved. In this regard, both the seating surface and the back frame may be tilted backwards simultaneously. Alternatively, only the back frame or the seating surface may be tilted.
Prior devices that have been developed in order to prevent the formation of pressure sores include cushion systems that are inflatable. These cushion systems employ air bags that can be inflated to different pressures or inflated at different locations on the wheelchair. Cushion systems thus seek to alternate the pressure points upon the individual's body thus reducing the occurrence of pressure sores. Prior devices have also been proposed that measure the amount of movement of the individual within his or her wheelchair. If an insufficient amount of movement is detected, the system assumes that the individual is not shifting his or her weight enough within the wheelchair and an alarm goes off informing the individual that a weight shift must be performed. Additional devices have been proposed that measure the amount of pressure the individual exerts onto the seat for a given time. If the amount of pressure for a given time is attained, the device signals the individual that it is time to perform a weight shift.
Previous attempts to reduce the formation of pressure sores, while enjoying a degree of success, are either too costly or are not easy to utilize over extended periods of time. Additionally, these systems are often complicated and signal alerts based upon a variety of detection parameters thus increasing the chances that the system may fail to issue a required alarm. Previous systems are not conservative in that they are designed to signal an alarm based on analyzing multiple conditions, such as pressure and time, to determine if these conditions justify issuing an alert. Although weight shifting is a good way to prevent pressure sores, to be effective the practice must become a habit.
As such, previous systems do not constantly signal an alert to an individual at predetermined time periods to ensure that weight shifting is being performed and to instill a sense of repetition so that constant weight shifting will become repetitious and hence second nature.
Accordingly, there remains room for variation and improvement within the art.